how to make your own giant pool of cornstarch

A few years ago, I wrote a post about Steve Spangler and the giant pool of cornstarch he used on the Ellen DeGeneres Show. Little did I know, Steve wrote up his little stunt!

Now, if you'd like to know how to make your own pool of cornstarch you can run across, you can follow Steve Spangler's instructions. You'll need:

• a container that is 7 feet long, 3 feet wide and about 1.5 feet deep
• roughly 2,400 pounds of cornstarch
• 240 gallons of water
• a cement mixer truck

A quick search unearths this place which apparently sells 50 pound bags of cornstarch for $50, which will set you back about $2400 for the amount you need. Even this place, which sells 50 pounds for the incredible price of $20 per pound will end up costing you $960. But, really, can you put a price on this kind of entertainment?

How does this demo work?

Cornstarch is simply starch derived from corn. "It is ground from the white endosperm at the heart of a kernel of corn. Cornstarch is used as a thickening agent in cooking, a health-conscious alternative to talc, and the main ingredient in a biodegradable plastic." (source)

When mixed with water, one concocts a fabulous substance affectionately referred to as oobleck, after the Dr. Seuss book. Real oobleck is made up of tiny, solid particles of cornstarch suspended in water.

From an Exploratorium source,

When you bang on it with a spoon or quickly squeeze a handful of Ooze, it freezes in place, acting like a solid. The harder you push, the thicker the Ooze becomes. But when you open your hand and let your Ooze ooze, it drips like a liquid. Try to stir the Ooze quickly with a finger, and it will resist your movement. Stir it slowly, and it will flow around your finger easily.

Your finger is applying what a physicist would call a sideways shearing force to the water. In response, the water shears, or moves out of the way. The behavior of Ooze relates to its viscosity, or resistance to flow. Water's viscosity doesn't change when you apply a shearing force--but the viscosity of your Ooze does.

Back in the 1700s, Isaac Newton identified the properties of an ideal liquid. Water and other liquids that have the properties that Newton identifies are call Newtonian fluids. Your Ooze doesn't act like Newton's ideal fluid. It's a non-Newtonian fluid.

Other non-Newtonian liquids include ketchup and quicksand. Check out the Science Friday video for other cool info and experiments.


What else can I do with cornstarch or oobleck?

You can put oobleck on a speaker and watch it (awesome clip #1 - oobleck starts at :58), awesome clip #2, awesome clip #3) Even The Big Bang Theory found this entertaining:

And apparently, according to the Hodgson company, there are about 1 million other uses for cornstarch.

You can read more about oobleck and quicksand on Steve Spangler's blog.

3D printers FTW!

A recent (12.10.11) article in the Economist couldn't come at a more perfect time. It's the start of Christmas break, I have free time to read it, and I have been the proud owner of a 3D printer for exactly one week. From the article:

[At] EUROMOLD, a big manufacturing trade fair held in Frankfurt from November 29th to December 2nd [2011], ... 300 or so exhibitors working in three-dimensional printing (or “additive manufacturing” as they prefer to call it).... Some of their 3D printers were the size of cars; others were desktop models. All worked, though, by building products up layer by layer from powered metal, droplets of plastic or whatever was the appropriate material.

I learned about many manufacturers who are using this process to imitate nature. For example:

• an artificial hip made by Materialise, a Belgian firm (see cool video featuring them)
  
• a load-bearing column constructed from filaments of concrete, imitating the basic design of plant stems, and printed by researchers at the Massachusetts Institute of Technology
• heat exchangers, whose best design resembles a fish gill (more surface area!), by a British firm called Within Technologies
• light, geodetic structures imitating a “cytoskeleton” of fibrous proteins that holds a cell in shape. The work is being done at Southampton University in Britain, where researchers have printed an unmanned aircraft from laser-sintered nylon (sintering is a way of making objects by heating powders, important for one of the videos below!) OMG - they PRINTED A PLANE!
  

That ability to create light, strong structures which have complex internal shapes may well turn out to be additive manufacturing’s killer app. The layering of powders or droplets that are then sintered into solidity, or cured with heat or ultraviolet light, allows spaces to be left inside the product. And if such a space would otherwise collapse, it can be filled with a powder that remains intact during curing and is then washed out or blown away. Even moving parts, like clock mechanisms, have thus been made in one go in a 3D printer.

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If you'd like to have your own 3D designs printed, there are companies like i.Materialize and Shapeways that will do it for you. Other folks have printed musical instruments, food, blood vessels (?!) and - in the case of this innovative San Francisco company - stylish prosthetics.

But, I've been much more interested in printing 3D objects myself. Preferably with my students, who are much more fearless with technology than I am.

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Back in 2008, I first became intrigued with 3D printers when I saw a RepRap at Maker Faire for the first time. They had me at "self-replicating machine." Apparently, if you built one printer, it could PRINT a second set of parts (minus the electronics, metal, etc) for you to build a second machine. This amazed me. Every year since, I have been back to gawk at their booth.

Years later, a student sent me a link to the video demonstrating one of ZCorp's 3D printers. Incredible! (If you want the very technical details about how this works, you can watch Michael Mock's explanatory video.)

Still, not something inexpensive enough for the classroom, although DIY 3D printers were coming down in price. At the 2011 Maker Faire, some 3D printers were selling for as low as $800. Some students and I got to brainstorming fundraisers, and I started looking for grant money.

In the fall of 2011, I attended the NextGen Science Fair and, not surprisingly, hung around the RepRap booth. There, I met Brook Drumm and learned about his plans to create Printrbot, an affordable 3D printer that "can be assembled and printing in a couple of hours." One of his goals is to get 3D printers into the hands of kids!

Fast forward to December 2011: The first Printrbots are ready (you should definitely read all about his Printrbot Kickstarter Project) and Brook came to our school to set up and train us on our very own 3D printer! What will we print? We will be able to use ready-made designs from Thingiverse, or design our own objects using the free programs Google SketchUp or Tinkercad. (One of my students has his gummy bear design ready!) As long as the design can be exported to a .stl file, and is within the boundaries of the Printrbot, we should be able to print it!

Check our the Printrbot and my middle school kids in the video below. The printer is quite new and we have a lot to learn, but it is tantalizing with its possibilities.

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Now, if you are still reading, you probably find 3D printing as fascinating as I do. Here are some other incredible videos:

3D Metal printing

Markus Kayser Solar Sinter

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And finally, as with all new technologies, there are new issues to consider. Affordable 3D printing brings up new considerations with copyright. Should be interesting to see how it all pans out.

QR codes are popping up all over!

Oh man, this post is long overdue. I started it years ago in November of 2010, when I saw my first QR code on a billboard in the Denver airport. At this point, I had seen QR codes on my United mobile boarding passes for a while, but this was the first time I saw one of the codes "out in the wild," so to speak.

Soon, I was seeing them everywhere! Bus stops, actual buses, catalogs, advertisements, even on a sticker on a bike rack outside the local Chipotle.

























Then, in April 2011, Chicago CBS shared a QR code story and Richard Byrnes (Free Technology for Teachers) wrote an awesome post on QR codes. Heck, by April, even my mom knew what a QR code was! :) Researchers even had developed a QR code-based vending machine that accepts PayPal. I realized it was time to go back and dig out my notes.

MY NOTES:

And I finally did it. I got a QR code app. I checked out this Feb 18, 2011 blog post describing 5 of the current iPhone apps for scanning QR codes and bar codes. I decided on Scan. The first thing I did was use it to access the NSTA mobile site for the 2011 national conference in SF. (The second thing I did was scan that (unlabeled) sticker on that bike rack. It was some ad about smoking cessation.)

I've learned that QR stands for "Quick Response" and has been around since 1994. QR codes were originally created by a company called the Denso Corporation and these 2D bar codes have been popular in Japan for some time. (see 2007 blog post, 2009 blog post)

How do they work?

Well, if you have some time, read the Wikipedia article on this one. Or this blog has more specific information on the QR code design process.

Image CC by Zephyris.

There are a few parts I can figure out:

• The three large squares (4.1) are the position markers. These tell the scanner where the edges of the code are.
• Then there is one (or more) smaller alignment squares (4.2), to make sure everything is in line.
• The dotted lines (4.3) are called "timing patterns" and define something about the position of the rows and columns.
• The pink section determines the format (2) - is it a website? a text message? Numbers? Letters? Chinese characters? A combination?

Want to generate your own QR code?

There are many, many options to create your own QR codes. In Sept 2010, TechCrunch wrote a post about Google's new URL shortener. Apparently, if you simply add “.qr” to the end of any goo.gl URL, it will create a QR code. Scanning this with any QR code reader will take you to the URL. Then in October, Bit.ly released it's own version of Google's little trick. Just add “.qr” to the end of any bit.ly link (including custom URL's) to generate a QR code.

This summer, while I was cavorting around in Alaska, I learned that you can create QR codes with an image in the center! One of the resident techies aboard the ship recommended BeQRious as a reliable site to try this.

I like the simplicity of this site. In fact, I used it to make the QR code on the back of my new business cards. :)

Holstee Manifesto

Love. This.

3 new elements named!

On November 4th, three new elements received their names. Of course, WebElements, periodic table on the web, was already on it! (Oh, and make sure to scroll down the WEbElements page and check out what the kids baked... I hope I have kids that cool one day. :)

Read about each new element:

• darmstadtium (110) - named after the city (Darmstadt, Germany) where it was originally synthesized (in 1994)
  
• roentgenium (111) - named in honor of the German physicist Wilhelm Conrad Röntgen, who first discovered X-rays
• copernicium (112) - named in honor of scientist and astronomer Nicolaus Copernicus
  

What's interesting to me is that these elements were first observed in a laboratory in 1994, 1994, and 1996, respectively, yet it took until 2011 for them to receive names. I read this fascinating post (from 2002) about how elements are named. Even then, the author writes,

It was only in 1997 that the International Union of Pure and Applied Chemistry, or IUPAC, proposed names for 104 - 109. These elements were created in laboratories in the United States, Russia, and Germany. Only a few atoms were created and they only existed for a short time. The naming of chemical elements is a matter of national and professional pride, however, and selecting a name these days requires a lot of bickering and bargaining. Elements 110, 111 and 112 have been created, but have yet to be named.

I liked reading the post and leaning more about how elements have been named using Latin symbols, the compounds they make up, Greek words, how the element was made, the place name where it was synthesized, mythology, and most recently, after famous scientists.

Well, armstadtium (110), roentgenium (111), and copernicium (112)... welcome to the Table!

bird garments: penguin sweaters & chicken jumpers

A link off the Chicago Tribune this morning about knitting penguin sweaters led me to a rather intensive research session on bird clothing. Who knew? Perhaps, I should clarify that I am only interested in dressing up animals when it serves some sort of rehabilitation purpose, as it does in these three stories. Dogs in frills for the amusement of their owners? Not so much. (All images are linked back to their original sources.)

First, penguin sweaters. It's true (snopes.com says so) that the Penguin Jumpers Project (now finished) collected over 15,000 jumpers to help rehabilitate Little penguins (Eudyptula minor - the smallest penguin species in the world) that have been affected by oil spills in Tasmania. As many of you may already know, a good washing with Dawn dish soap will clean the feathers of oil, but often the birds are too sick to be handled and washed right away. In the meantime, these sweaters are put on the birds so that the birds will not preen their feathers, potentially poisoning themselves with the oil. When their strength returns, the birds are washed and the insulating and waterproofing properties of the features restored.

Another group was asking for donations of jumpers... for chickens! When chickens are cooped up against each other in hot sheds at battery farms, the can often lose their feathers. Then, if they are fortunate enough to be rescued and moved to free-range conditions, they do not have the feathers to keep their bodies warm in the open fields. According to the rescue group Little Hen Rescue, "Not all farmed hens [we rescue] are bald, but usually there is around 10-20% that are, these hens depending on the time of year stay with us until feathered." While they are growing their feathers back, many of them will be wearing these donated jumpers.

Check out Little Hen Rescue's page for more pictures of hens in jumpers. Or check out a video here. Or see Paul Howard's Picassa album for my favorite picture of hen jumpers.)

Finally, if I am discussing bird garments, I can't leave out the story of Pierre, a penguin at the California Academy of Sciences in San Francisco, CA. By penguin standards, Pierre is an old bird. In the wild, penguins live about 15 years; in captivity, they live to about 20. Pierre turned 28 last February. When he was 25, he molted, and never grew back his feathers. When it was determined that there was no health-based reason for his balding, senior aquatic biologist & penguin handler, Pam Schaller came up with a creative solution - she collaborated on a penguin-sized wetsuit, which Pierre wore until his feathers and his demeanor recovered.

It's a great story. To learn more you can:

• check out his story in this children's book (2010)
• watch this KRON4 video (start at :50) (2008)
• listen to an npr broadcast (2008)
• read his recent history on the Cal Academy Penguin Blog (2011)
• download this Cal Academy document which includes all of the details of why he needed, how they designed, and who made the penguin wetsuit. It's fascinating!
  

In 2009, another wet-suit-wearing Cal Academy penguin made the news. Ralph, a nine year old Humboldt penguin, also had a similar wetsuit experience.

quark song

Today, a student introduced me to the Vlogbrothers (YouTube Channel). Hank and John Green are brothers who make nerdy videos. Hank lives in Montana, and John lives in Indiana, yet they still engage in nerdy collaboration across the miles.... Apparently, it all started in 2007, when the brothers chose to refuse text communicate and only communicated through voice and vlogs for the year.

The video below is one of Hank's songs, Strange Charm. It's about quarks. Quarks are a type of particle that makes up matter. Most of the matter we see around us is made from protons and neutrons, which are composed of quarks. The most recently discovered quark (the top quark) was announced in 1995! (A shout-out to Fermi National Accelerator Laboratory near Chicago, IL for the discovery!)

There are 6 types, or "flavors" of quarks: up, down, charm, strange, top, bottom. Each quark carries a fractional charge, and a color charge. (?!) According to the theory of quantum chromodynamics, quarks are always combined in groups of three quarks (of different colors) or as pairs consisting of a quark and an antiquark (of the same color). (??!!) This is more than my brain can handle, but it is pretty cool.

If you want to learn more about quarks, I suggest visiting the following sites:

• Need a refresher on atomic structure? Visit the Chem4Kids page or watch a Khan Academy video about atoms.
  
• Quarks page on particleadventure.org
• Howstuffworks - Quarks
  

Hank Green is also known for his blog, EcoGeek, which he began in graduate school as a class assignment!

Bike performance on China's Got Talent

I live in a town that has a bike polo league, a synchronized bike ballet, and the Bay Area Dérailleurs, a bicycle inspired dance team... but I have never seen anything like this!

From China's Got Talent... 16 girls on a bike! Not to mention a lot of jumping and flipping. Incredible.

Thanks to the "related videos," I also learned about 23 year old Liu Wei from Beijing, who won the China's Got Talent Show on Oct. 10, 2010. He swims competitively, and plays piano... yet he lost his arms in an accident when he was 10 years old. His attitude & determination are inspirational. You can watch his amazing performance here.